“…Several hypotheses have been proposed to explain the observed differences in colonoscopy efficacy between the distal and proximal colon. These include lesser quality of colon cleansing in the proximal than in the distal colon, and the importance of trained and experienced endoscopists; indeed, the proximal colon may be difficult to reach and explore properly, especially in women [23]. In addition, proximal adenomas are often flat, and difficult to identify and remove [24], even by an experienced endoscopist.…”